Method and apparatus for welding a fluoropolymer seam

ABSTRACT

A method for sealing and smoothing a seam produced from applying flexible protective covering sheets of a fluoropolymer to a hull of a marine craft, thus forming a protective fluoropolymer film on the hull. The method comprises placing a thread of fluoropolymer caulk onto the seam produced from applying the flexible protective covering sheets and applying sufficient heat and pressure to the thread of fluoropolymer caulk to melt and weld the fluoropolymer caulk with the fluoropolymer of the flexible protective covering sheets. The method includes smoothing the melted fluoropolymer caulk to produce a smooth seam with a sealed and smooth surface.

FIELD OF THE INVENTION

The present invention relates generally to applying flexible protective covering sheets of a fluoropolymer to a hull of a marine craft and more particularly, to smoothing and sealing the seams produced from applying the flexible protective covering sheets.

BACKGROUND OF THE INVENTION

The novel subject matter provided herein discloses an improvement to the subject matter of U.S. Pat. No. 5,769,019 (Inventor: Luis F. Dias da Silva, Date of Patent: Jun. 23, 1998) which is hereby incorporated by reference in its entirety.

Hulls of marine craft may develop marine growth and inorganic deposits when left in water for long periods of time. Not only is the aesthetic beauty of the marine craft affected, but the deposits may add to the overall weight and increase the friction or resistance between the hull and the water as the craft travels through the water. An increased drag resistance and weight may decrease the speed of the marine craft and thus impact the performance of the marine craft. The da Silva patent describes flexible protective covering sheets composed of a fluoropolymer applied to the hull of the marine craft, the covering sheets having one side with an adhesive for adhering to the hull.

The da Silva patent describes a solution wherein the fluoropolymer used for the flexible protective covering sheets is polytetrafluoroethylene (PTFE). Although PTFE has a drag resistance lower than other fluoropolymers, PTFE is relatively soft and easily damaged. A fluoropolymer which better withstands salt spray and abrasion, while still providing an extremely low coefficient of friction, is ethylene tetrafluoroethylene (ETFE). A second best performing fluoropolymer is fluorinated ethylene propylene (FEP), which offers a slightly improved coefficient of friction over ETFE, but is not as hard and does not withstand wear or abrasion as well as ETFE. Although the patent by da Silva suggests using PTFE as the fluoropolymer in the flexible protective covering sheets, ETFE provides a better choice. ETFE is harder and less easily damaged than PTFE.

Although the patent of da Silva discloses applying flexible protective covering sheets of fluoropolymer to the hull of a marine craft, the seaming methodology described is different and results in an ineffective seam. The seams produced from the application of the flexible protective covering sheets still provide some drag resistance to the overall performance of the marine craft. The patent by da Silva suggests use of a caulk to fill the seams. However, the property of a fluoropolymer that prevents adhesion of contaminants, such as marine growth and inorganic deposits, to the hull also prevents a caulk from sticking to the hull very well. Seams created by butting two sheets of fluoropolymer film against each other must be absolutely flush to provide the expected anti-fouling qualities while maintaining the integrity of the seam and sheets of film. Any gap in the seam creates a point of entry for marine life to attack the underlying hull and attach themselves chemically to the boat. The method described in daSilva for applying a caulk to the hull will not fill the seam because the caulk will not adhere to the surfaces of the adjoining sheets of fluoropolymer film. The method of creating an overlapping seam using two adjoining pieces of fluoropolymer film is equally flawed. The adhesive on the underside of the overlapping piece of film is not sufficient to permanently adhere the two pieces of film together. While the adhesive will hold the overlap in place, the pressures created on the seam at normal operating speeds will cause the seam to break and the pieces of film to separate from the hull. The seams must be sealed close using heat and pressure alone or in conjunction with a thread of melted fluoropolymer in order to withstand normal operating stresses of direct and back pressure

An improvement is still needed to effectively smooth and seal the seams produced from applying flexible protective fluoropolymer covering sheets to the hull of a marine craft.

SUMMARY OF THE INVENTION

In one embodiment, a method is provided for sealing and smoothing a seam produced from applying flexible protective covering sheets of a fluoropolymer to a hull of a marine craft. The seam may be produced by butting the edges of two fluoropolymer covering sheets to each other (a butt-cut seam) or may be produced by overlapping the edges of two fluoropolymer covering sheets (an overlapped seam). A heating device, e.g. a modified soldering iron, or other suitable heating device, is provided either for melting the fluoropolymer of the seam or for applying a melted fluoropolymer caulk to the seam, thus sealing and smoothing the seam.

In another embodiment, a method is provided comprising: placing a thread of fluoropolymer caulk onto the seam produced from applying the flexible protective covering sheets; applying sufficient heat and pressure to the thread of fluoropolymer caulk to melt and weld the fluoropolymer caulk with the fluoropolymer of the flexible protective covering sheets; and smoothing the melted fluoropolymer caulk to produce a smooth seam having a smoothly sealed surface.

In yet another embodiment, a method is provided comprising: applying sufficient heat and pressure to the seam to melt and weld the seam of fluoropolymer of adjacent flexible protective covering sheets; and smoothing the melted seam to produce a smooth seam having a smoothly sealed surface.

In still yet another embodiment, a protected marine craft hull is provided, comprising: a hull having an external portion covered with flexible fluoropolymer covering sheets adhered to the hull; the flexible fluoropolymer covering sheets being arranged with at least two adjacent flexible fluoropolymer covering sheets meeting and forming a seam; and the seam having a smooth and sealed surface produced through an application of sufficient heat and pressure at the seam.

In another embodiment, an apparatus is provided for applying heat and pressure to a fluoropolymer seam to melt and weld the fluoropolymer of the seam into a seam having a smoothly sealed surface, comprising: a heating device having a heating surface suitable for applying the heat and pressure to the fluoropolymer seam; and a thread roll apparatus having a thread roll spool configured to have a spool of fluoropolymer caulk and a thread roll guide for guiding the fluoropolymer caulk onto the fluoropolymer seam.

In another embodiment, an apparatus is provided for applying heat and pressure to a fluoropolymer seam to melt and weld the fluoropolymer of the seam into a seam having a smoothly sealed surface, comprising: a heating surface for heating a portion of a flexible heat strap; and the flexible heat strap configurable to have a shape of at least one of a flat surface, a concave surface, and a convex surface for applying the heat and pressure correspondingly, to at least one of a flat fluoropolymer surface, a convex fluoropolymer surface, and a concave fluoropolymer surface.

In another embodiment, an apparatus for sealing the seam between two abutting sheets of fluoropolymer film is provided, the apparatus comprising: a thread roll apparatus having a thread roll spool configured to have a spool of fluoropolymer caulk; a thread roll guide for guiding the fluoropolymer caulk onto the fluoropolymer seam; a heating apparatus for heating at least a portion of the spool of fluoropolymer caulk; and a trowel member for spreading the fluoropolymer caulk on the seam after dispensing.

In yet another embodiment, an apparatus is provided for applying heat and pressure to a fluoropolymer seam to melt and weld the fluoropolymer of the seam into a seam having a smoothly sealed surface, comprising: a heating device having a heating surface suitable for applying the heat and pressure to the fluoropolymer seam; and a glue gun apparatus for pre-heating a fluoropolymer caulk before application of the fluoropolymer caulk to the seam.

In another embodiment, a flexible guide rail apparatus is provided, comprising: a flexible guide rail strip adapted for guiding a heating device along a fluoropolymer seam; and at least one of a plurality of suction cups fitted to the flexible guide rail strip to allow coupling of the flexible guide rail strip to a surface.

DETAILED DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood in view of the following description when accompanied by the below figures and wherein like reference numerals represent like elements.

FIGS. 1A-1C illustrate an example of a method for sealing and smoothing a butt-cut seam produced from applying flexible protective covering sheets of a fluoropolymer to a marine craft hull in accordance with an embodiment of the invention;

FIGS. 2A-2B illustrate an example of a method wherein a thread of fluoropolymer caulk is not used to seal and smooth an overlap seam in accordance with an embodiment of the invention;

FIGS. 3A-3C illustrate an example for sealing and smoothing an overlap seam in accordance with an embodiment of the invention;

FIGS. 4A-4C illustrate an example of a heating device suitable to apply sufficient heat and pressure for a melting and welding process in accordance with an embodiment of the invention;

FIG. 5 illustrates an example of a thread roll apparatus used in placing a thread of fluoropolymer caulk in accordance with an embodiment of the invention;

FIGS. 6A-6E show an example of a heating apparatus used in applying sufficient heat and pressure in accordance with an embodiment of the invention;

FIG. 7 shows a flowchart describing one example of a method for sealing and smoothing a seam in accordance with an embodiment of the invention;

FIG. 8 illustrates an example of an apparatus, the apparatus being a variation on the apparatus of FIG. 5;

FIG. 9 illustrates an example of an apparatus, the apparatus being a variation on the apparatus of FIG. 8.

FIGS. 10A-10B illustrate an example of a glue gun apparatus modified in accordance with an embodiment of the invention.

FIGS. 11A-11B illustrate yet another example of a glue gun apparatus modified in accordance with an embodiment of the invention.

FIGS. 12A-12B illustrate an example of a flexible guide rail apparatus for use in guiding the movement of a glue gun apparatus in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1A-1C illustrate one example of a method for sealing and smoothing a butt-cut seam 104 produced from applying flexible protective covering sheets 102 and 103 of a fluoropolymer to a hull 100 of a marine craft in accordance with an embodiment of the invention. The flexible protective covering sheets 102 and 103 may be applied to structures other than a marine craft, for example surfaces of dock pilings/platforms, pontoons, navigational buoys, submersibles, snowmobiles, airplanes, and the like. As shown in FIG. 1A, the flexible protective covering sheets 102 and 103 have one side adhered to the hull 100 due to the one side having an adhesive backing which allows the flexible protective covering sheets 102 and 103 to stick to the hull 100. As shown in FIG. 1A, the flexible protective covering sheets 102 and 103 are cut to be fitted and butted against each other when applied to the hull 100. The butt-cut seam 104 is produced when two adjacent flexible protective covering sheets 102 and 103 are applied to the hull 100. As shown in FIG. 1B, a thread 106 of fluoropolymer caulk is placed onto the butt-cut seam 104. Use of a heating device, such as a soldering iron (shown in FIGS. 5, 8,9), supplies sufficient heat and pressure to the thread 106 to melt and weld the thread 106 with the fluoropolymer of the flexible protective covering sheets 102 and 103. The heating device may also have a smoothing surface to be used to smooth the melted thread 106 and produce a smooth seam 108 with a sealed and smooth surface. FIG. 1C shows the smooth seam 108 produced from melting and welding the thread 106 of fluoropolymer caulk into the butt-cut seam 104.

FIGS. 2A-2B illustrate another example of a method wherein the thread 106 of fluoropolymer caulk of FIG. 1B is not used to seal and smooth an overlap seam 110 in accordance with an embodiment of the invention. As shown in FIG. 2A, the overlap seam 110 is produced from overlapping edges 112 and 114 of corresponding adjacent flexible protective covering sheets 116 and 118 that are applied to a hull 120. Sufficient heat and pressure when applied directly to the overlapping edges 112 and 114 by a heating device, such as a soldering iron (shown in FIGS. 5, 8, 9) or some other suitable heating device, melt and weld the fluoropolymer of the overlapping edges 112 and 114. The heating device may also have a smoothing surface to be used to smooth the melted overlapping edges 112 and 114 to produce a smooth seam 122 with a smoothly sealed surface as shown in FIG. 2B.

FIGS. 3A-3C illustrate yet another example for sealing and smoothing an overlap seam 110 in accordance with an embodiment of the invention. As shown in FIG. 3A, a seam 129 is produced from overlapping edges 128 and 130 of corresponding adjacent flexible protective covering sheets 124 and 126 which have been applied to a hull 132. In FIG. 3B, a thread 134 of a fluoropolymer is placed onto the seam 129 and melted with sufficient heat and pressure to weld the thread 134 to the fluoropolymer of the overlapping edges 128 and 130. The melted and welded thread 134 of fluoropolymer is smoothed by the heating device to produce a smooth seam 136 with a smoothly sealed surface.

Relating back to FIG. 1A, yet another embodiment may be provided by applying sufficient heat and pressure directly to the butt-cut seam 104 to melt and weld the fluoropolymer of the butt-cut seam 104 without the use of the thread 106 of fluoropolymer. However, this embodiment is probably inferior to the previous described embodiments as the melted and welded butt-cut seam 104 will probably result in a thinner layer of fluoropolymer than the film layer of the covering sheets 102 and 103.

FIGS. 4A-4C illustrate an example of a heating device 400 suitable to apply sufficient heat and pressure for the melting and welding process in accordance with an embodiment of the invention. The heating device 400 includes adapter 402 and a wheel tip 404, the adapter 402 configured to be fitted to a soldering iron, for example, having a threaded end 403 for screwing into a soldering iron. The wheel tip 404 is rollable and free spinning around an axle 406. The heating device 400 is shown from a side view in FIG. 4A. In FIG. 4B another side view 410 is shown rotated 90° from that of FIG. 4A. FIG. 4B shows the axle 406 from a side view with a clear perspective of the rotatable wheel tip 404. The surface of the wheel tip 404 may be flat or suitably shaped to apply heat and pressure for the melting and welding process described herein. FIG. 4C shows a top view 420 of the heating device 400. The heating device 400 is an example of an apparatus for applying heat and pressure to a fluoropolymer seam to melt and weld the fluoropolymer of the seam into a seam having a smoothly sealed surface. The surface of the wheel tip 404 provides a heating surface suitable for applying the heat and pressure to the fluoropolymer seam.

FIG. 5 illustrates one example of an apparatus 500 wherein a thread roll apparatus 516 includes a thread roll spool 504 and a thread roll guide 508 attached to a heating device 502, e.g. a soldering iron. The corresponding clamps 514 and 512, or some other suitable mechanism, attach the thread roll apparatus 516 to the heating device 502. The thread roll spool 504 has a spool of fluoropolymer caulk and provides a thread 510 of fluoropolymer caulk which is guided by the thread roll guide 508 onto a fluoropolymer seam (shown as 104 of FIG. 1 and 129 of FIG. 3) to be sealed and smoothed by the melting and welding process. A suitable wheel tip 506 of the apparatus 500 supplies sufficient heat and pressure to the thread 510 of fluoropolymer caulk to melt and weld the thread 510 with the fluoropolymer of the covering sheets 102 and 103 (FIG. 1C), thus producing a smooth seam 108.

FIGS. 6A-6E show an example of yet another heating apparatus 600 in accordance with an embodiment of the invention. FIG. 6A shows a side view of the heating apparatus 600. The heating apparatus 600 includes a heating source 602, a piston 604, a tension spring hinge 606, a flexible heat strap 608, and a flexible heat surface 610 to be heated by a flexible heat element 619. Also included is a handgrip 616, an electrical cord 614 and an on/off switch 612. When the on/off switch 612 is on, the cord 614 supplies electrical energy to the heating source 602 which transforms the electrical energy into heat to heat the flexible heat surface 610. The piston 604 with the tension spring hinge 606 allow for changing the curvature of the flexible heat strap 608. The curvature of the flexible heat strap 608 is discussed further in FIGs. below. The tension spring hinge 606 supplies tension to the flexible heat strap 608 to adjust the tightness of the flexible heat strap 608.

FIG. 6B illustrates the heating apparatus 600 as seen from a front view. The flexible heat surface 610 is of suitable width 618, for example 3/4 of an inch, for supplying heat and pressure to a portion of the flexible heat strap 608. The portion of the flexible heat strap 608 applies heat and pressure to a seam, e.g. the butt-cut seam 104 and fluoropolymer thread 106 (FIG. 1B) or the overlapped seam 129 and fluoropolymer thread 134 (FIG. 3B).

As shown in FIG. 6C, the heating apparatus 600 applies heat and pressure to a seam, e.g. the butt-cut seam 104 of FIG. 1A, formed by adjacent covering sheet 603. A hull 601 and the covering sheets 603 show a fairly flat surface 620. In this case the piston 604 is neither retracted nor depressed and with the tension of the tension spring hinge 606, configures the flexible heat strap 608 to be flat. In comparison, FIG. 6D shows a convex surface 622. The heating apparatus 600 has the piston 604 retracted and the tension of the tension spring hinge 606 adjusted to configure the flexible heat strap 608 to have a convex curvature in accordance with the convex surface 622. Alternatively, FIG. 6E shows a concave surface 624 for which the heating apparatus 600 is adjusted. In this situation, the piston 604 is depressed and the tension of the tension spring hinge 606 adjusted to configure the flexible heat strap 608 to have a concave curvature in accordance with the concave surface 624.

FIG. 7 shows a flowchart describing one example of a method 700 for sealing and smoothing a seam in accordance with an embodiment of the invention. The method 700 begins at 701 with the flexible protective covering sheets 102 and 103 having been applied to the hull 100 (FIG. 1A). As shown in block 702, a fluoropolymer thread 106 (FIG. 1B) is placed onto the butt-cut seam 104 and at 704, sufficient heat and pressure is applied to the thread 106 to melt and weld the thread 106 of fluoropolymer caulk with the fluoropolymer of the protective covering sheets 102 and 103. As shown in block 706, smoothing takes place whereby the smooth seam 108 with a smooth sealed surface is produced. The method 700 is repeated for all seams and ends at 707 with smooth seams 108 for the hull 100.

FIG. 8 illustrates an example of an apparatus 800, the apparatus 800 being a variation on the apparatus 500 of FIG. 5. Shown in FIG. 8 are a thread roll apparatus 516, the thread roll apparatus 516 including a thread roll spool 504 and a thread roll guide 508 attached to a heating device 502, e.g. a soldering iron, as discussed previously in FIG. 5. However, the wheel tip 506 is replaced with a chisel tip 818 configured to be attached to the heating device 502 for applying heat and pressure to a fluoropolymer seam. In addition, a heating apparatus 811 for heating at least a portion of the thread roll spool 504 of fluordpolymer caulk is attached to the heating device 502 by a clamp 813 or some other suitable mechanism. Also, a trowel member 820 is attached to the heating device 502 by a clamp 822 or some other suitable mechanism. The trowel member 820 helps spread the fluoropolymer caulk on the seam after dispensing. The chisel tip 818 supplies sufficient heat and pressure to the pre-heated thread 510 of fluoropolymer caulk to melt and weld the thread 510 with the fluoropolymer of the covering sheets 102 and 103 (FIG. 1C), thus producing a smooth seam 108.

FIG. 9 illustrates an example of an apparatus 900, the apparatus 900 being a variation on the apparatus 800 of FIG. 8. The thread roll apparatus 516, and the heating apparatus 811 of FIG. 8 are replaced by the glue gun apparatus 902. The glue gun apparatus 902 includes fluoropolymer caulk (not shown in FIG. 9) and pre-heats the fluoropolymer caulk to a temperature of at least approximately 500 degrees Fahrenheit (F.) for dispensing. The glue gun apparatus 902 is attached to the heating device 502 by use of a clamp 904 or some other suitable mechanism. A guide adapter (not shown in FIG. 9, but an example of which is shown in FIG. 10) may also be attached by a clamp or suitable mechanism to the apparatus 900. The guide adapter may be designed for use with a flexible guide rail apparatus for guiding the apparatus 900 along a fluoropolymer seam. Use of the flexible guide rail apparatus is described further herein.

FIGS. 10A-10B illustrate an example of a glue gun apparatus 1000 modified in accordance with one embodiment. In the example of FIG. 10A, a Nordson® AD-41 glue gun from Nordson Corp. of Duluth, Ga. has been modified to have a guide adapter 1010, for example the guide adapter 1010 as shown with one or more guide pins 1020. Glue guns and glue gun machinery from companies other than Nordson may be used and adapted as well. The guide pins 1020 may be fitted to a tripod or other suitable apparatus that couples to a sliding carriage of a flexible guide rail apparatus for guiding the movement of the glue gun apparatus 1000 along a fluoropolymer seam. Additionally, the glue gun, (or the soldering iron), may have a laser (not shown in the figure) configured to produce a laser light onto the seam to assist a user of the glue gun in guiding the glue gun along the seam. The fluoropolymer material supply tube 1030 supplies pre-melted and pre-heated fluoropolymer caulk, e.g. FEP, to a nozzle tip 1040 when squeezing a trigger 1050 of a handle 1060 of the glue gun. The handle 1060 may be reconfigured (not shown in the figure) to be a reverse handle for use in a more upright or vertical position than a horizontal position. In this case, the nozzle tip 1040 may be located more to the rear of the glue gun than, as shown in FIG.10A, at the front of the glue gun.

FIG. 10B shows further modification to the glue gun apparatus 1000 with the addition of a trowel member 1070. The trowel member 1070 may be useful in spreading and flattening the fluoropolymer caulk at the seam after dispensing the pre-melted fluoropolymer caulk through the nozzle tip 1040. As the glue gun apparatus 1000 dispenses a layer of FEP beads 1080 to the seam of a hull 1090, the trowel member 1070 follows the FEP beads 1080 flattening the FEP beads 1080 at the seam to form a smooth and sealed surface.

FIGS. 11A-11B illustrate yet another example of a glue gun apparatus 1100 modified in accordance with one embodiment. In the example of FIG. 11A, a Champ 5 glue gun from Glue Machinery Corporation™ of Baltimore, Md. has been modified to have a guide adapter 1110, for example the guide adapter 1110 as shown with one or more guide pins 1120. The guide pins 1120 may be fitted to a tripod or other suitable apparatus that couples to a sliding carriage of a flexible guide rail apparatus for guiding the movement of the glue gun apparatus 1100 along a fluoropolymer seam. Additionally, the glue gun may have a laser (not shown in the figure) configured to produce a laser light onto the seam to assist a user of the glue gun in guiding the glue gun along the seam. The fluoropolymer material supply tube 1130 supplies pre-melted and pre-heated fluoropolymer caulk, e.g. FEP, to a nozzle tip 1140 when squeezing a trigger 1150 of a handle 1160 of the glue gun. The handle 1160 may be reconfigured (not shown in the figure) to be a reverse handle for use in a more upright or vertical position than a horizontal position. In this case, the nozzle tip 1140 may be located more to the rear of the glue gun than, as shown in FIG. 11A, at the front of the glue gun.

FIG. 11B shows further modification to the glue gun apparatus 1100 with the addition of a trowel member 1170. The trowel member 1170 may be useful in spreading and flattening the fluoropolymer caulk at the seam after dispensing the pre-melted fluoropolymer caulk through the nozzle tip 1140. As the glue gun apparatus 1100 dispenses a layer of FEP beads 1180 to the seam of a hull 1190, the trowel member 1170 follows the FEP beads 1180 flattening the FEP beads 1180 at the seam to form a smooth and sealed surface.

A server motor may be employed to advance the glue gun apparatus 1000 or the glue gun apparatus 1100 in the flexible guide rail apparatus at a controlled speed. A server motor may also be employed to pump the pre-melted fluoropolymer caulk through the nozzle tip 1040 at a constant pneumatic pressure.

FIGS. 12A-12B illustrate an example of a flexible guide rail apparatus 1200 for use in guiding the movement of a glue gun apparatus, e.g. the glue gun apparatus 1000 of FIGS. 10A-10B or the glue gun apparatus 1100 of FIGS. 11A-11B, or a soldering iron as shown in FIG. 5 or FIG. 8, along a fluoropolymer seam. FIG. 12A shows a tripod apparatus 1210 coupled to a flexible guide rail strip 1220. The guide pins 1020 of the guide adapter 1010 of FIG. 10A may be fitted to the tripod apparatus 1210 in order to couple the glue gun apparatus 1000 to the flexible guide rail strip 1220. The flexible guide rail strip 1220 is adapted for guiding the movement of a heating device, e.g. a glue gun apparatus or a soldering iron, along the fluoropolymer seam. Additionally, the flexible guide rail strip 1220 may be configured with a laser (not shown in the figure) to produce a visible laser beam line along the fluoropolymer seam to assist a user in guiding the heating device along the fluoropolymer seam in a straight line. Although of possible use when a hull 1240 is a fairly flat surface, the laser may not be of much use with the flexible guide rail strip 1220 that is curved to follow a curved surface of the hull 1240.

At least one of a plurality of suction cups 1230 may be affixed to the flexible guide rail strip 1220 to allow coupling of the flexible guide rail strip 1220 to a surface, e.g. the surface of the hull 1240 of a marine craft. The suction cups 1230 may be positioned along the flexible guide rail strip 1220 to maintain the flexible guide rail strip 1220 at approximately the same height above the surface of the hull 1240. The material of the flexible guide rail strip 1220 may be pliable and bendable to bend over a curved surface and follow the curve, such as a curved surface of the hull 1240.

FIG. 12B shows the flexible guide rail apparatus 1200 from a top view with the addition of a sliding carriage 1250. The sliding carriage 1250 is coupled to the flexible guide rail strip 1220 and configured to slide along the flexible guide rail strip 1220. The sliding carriage 1250 may have an adjustment, e.g. screw adjustments (not shown in the figure), or other suitable mechanism for tightening the sliding carriage 1250 to the flexible guide rail strip 1220. The force required to move or slide the glue gun apparatus 1000 along the flexible guide rail strip 1220 as fluoropolymer caulk is dispensed onto a seam 1260 may be adjusted by adjusting the screw adjustments of the sliding carriage 1250 to which the glue gun apparatus 1000 is coupled. In one embodiment, the tripod apparatus 1210 may be fitted to the sliding carriage 1250. In an alternative embodiment, the tripod apparatus 1210 may have bearing wheels fitted to roll in a groove of the flexible guide rail strip 1220 without the use of the sliding carriage 1250. As known in the art, other suitable mechanisms may be implemented to hold or couple a heating device, e.g. the glue gun apparatus 1000 of FIG. 10A or a soldering iron, e.g. the soldering iron of FIG. 5 or FIG. 8, to the flexible guide rail strip 1220 allowing movement of the heating device along the flexible guide rail strip 1220. As a further use of the sliding carriage 1250, the sliding carriage 1250 may be configured to have a knife, e.g. an exacto knife (not shown in the figure). The sliding carriage 1250 may be configured to adjust the height or depth of the knife for cutting through one or more layers of fluoropolymer film/sheets without cutting the hull 1240. The sliding carriage 1250 with the exacto knife arrangement may be used to cut sheets of fluoropolymer to be butted against each other when adhered to the hull 1240 to form butt-cut seams.

A first flexible guide rail strip 1220 may be configured to have a second flexible guide rail strip 1220 coupled or interlocked with the first to extend the overall length of the flexible guide rail strip 1220. For example, the first flexible guide rail strip 1220 may be configured to snap together with another, and/or to interlock with one another. In extending the length of the flexible guide rail strip 1220, the suction cups 1230 may be configured to be removable from the flexible guide rail strip 1220 to allow passage of the glue gun apparatus 1000.

The suction cup 1230 may be configured to allow diminishing the suction pressure of the cup to allow movement of the suction cup 1230 in order to realign the flexible guide rail strip 1220. This may be achieved in a number of ways. For example, an internal cam or lever may be affixed to the suction cup 1230 to apply an upward force to the suction cup 1230 when one end of the lever or cam is depressed so as to allow movement of the suction cup 1230. In an alternative embodiment, the suction cup 1230 may be configured with a vent button or other suitable mechanism that when depressed, releases some of the suction pressure of the cup, allowing the cup to be moved. In yet another embodiment, a lip of the suction cup 1230 may be designed to allow sliding a pry tool under the lip to pry the cup loose.

A servo motor may be employed to advance the glue gun apparatus 1000 or the glue gun apparatus 1100 in the flexible guide rail strip 1220 at a controlled speed. The servo motor may also pump the pre-melt through the

In the aforementioned disclosure, reference has been made to a fluoropolymer, e.g. the fluoropolymer of the flexible protective covering sheets 102 and 103 or the fluoropolymer of the thread 106 of fluoropolymer caulk. In one embodiment, the fluoropolymer of the flexible protective covering sheets 102 and 103 consist of ETFE. ETFE has a melting point of about 512° F and an extremely low coefficient of friction, as well as a hardness that is not as easily damaged as the fluoropolymer PTFE. With regard to the use of a fluoropolymer for the thread 106 of fluoropolymer caulk, FEP serves fairly well. FEP has a melting point of about 500° F., just slightly lower than the melting point of ETFE. FEP has a slightly improved coefficient of friction over the coefficient of friction of ETFE, but is not as hard as ETFE. Thus, FEP may provide a very suitable caulking substance for smoothing and sealing the ETFE seams 104 produced from applying the flexible protective covering sheets 102 and 103. Regarding a heating device, an 80 watt Weller soldering iron capable of about 900 degrees F. has been found to be suitable. The tip temperature of the soldering iron in the range of about 750-800 degrees F. has been found to work well and to allow for dissipation of heat during the application of heat to melt the fluoropolymer.

Although fluoropolymer sheets may be adhered to a non-metallic hull of a marine craft, fluoropolymer sheets may be adhered to a metallic surface, e.g. the hulls of naval vessels or the metallic wings of an aircraft. In this case, a co-polymer or multi-layer laminate may have a glue or adhesive, e.g. a 9471 LE adhesive from 3M or Thi/t adhesive from Dyneon, on one side or surface of the multi-layer laminate capable of sticking and adhering the multi-layer laminate to a metallic surface. The embodiments described herein may be used to seal and smooth the seams formed from the use of multi-layer fluoropolymer laminates.

The methods disclosed herein provide for an improvement to the da Silva patent. The disclosures herein address an improvement to hull efficiency through the reduction of the hull's coefficient of friction, leading to improved speed and/or improved fuel consumption (as great as 10% based on trials to date).

The above detailed description of the invention and the examples described therein have been presented for purposes of illustration and description only and not by limitation. It is therefore contemplated that the present invention cover any and all modifications, variations or equivalents that fall within the spirit and scope of the basic underlying principles disclosed above and claimed herein. 

1. A method for sealing and smoothing a seam produced from applying flexible protective covering sheets of a fluoropolymer to a hull of a marine craft, so as to form a protective film on an exterior of the hull, said method comprising: placing a thread of fluoropolymer caulk onto the seam produced from applying the flexible protective covering sheets; applying sufficient heat and pressure to the thread of fluoropolymer caulk to melt and weld the fluoropolymer caulk with the fluoropolymer of the flexible protective covering sheets; and smoothing the melted fluoropolymer caulk to produce a smooth seam having a smoothly sealed surface.
 2. The method according to claim 1, wherein the method comprises: overlapping adjacent edges of adjacent flexible protective covering sheets to produce an overlap seam; and placing a thread of fluoropolymer caulk onto the overlap seam.
 3. The method according to claim 1, wherein the method comprises: butting together butt-cut edges of adjacent flexible protective covering sheets to produce a butt-cut seam; and placing a thread of fluoropolymer caulk onto the butt-cut seam.
 4. The method according to claim 1, wherein the method comprises feeding the thread of fluoropolymer caulk onto the seam from a thread roll apparatus.
 5. The method according to claim 4, and further comprising feeding said thread of fluoropolymer caulk from a thread roll apparatus comprising a thread roll spool with spooled fluoropolymer caulk and a thread guide for guiding the thread of fluoropolymer caulk onto the seam.
 6. The method according to claim 5, and further comprising heating said fluoropolymer caulk with a heating device.
 7. The method according to claim 6, wherein said heating device comprises a soldering iron.
 8. The method according to claim 1, wherein said steps of applying sufficient heat and pressure, and smoothing the melted fluoropolymer caulk, comprise applying a soldering iron, an end of the soldering iron having a rollable wheel tip, the rollable wheel tip having a facial surface at the circumference suitably shaped for smoothing the melted fluoropolymer caulk as the wheel tip is rolled across the seam, applying sufficient heat and pressure through said rollable wheel tip to melt and weld the fluoropolymer caulk with the fluoropolymer of the flexible protective covering sheets.
 9. The method according to claim 1, wherein said steps of applying sufficient heat and pressure, and smoothing the melted fluoropolymer caulk, comprise applying a soldering iron, an end of the soldering iron having a chisel tip, the chisel tip suitably shaped for smoothing the melted fluoropolymer caulk as the chisel tip is moved across the seam, applying sufficient heat and pressure through said chisel tip to melt and weld the fluoropolymer caulk with the fluoropolymer of the flexible protective covering sheets.
 10. The method according to claim 1, wherein the fluoropolymer caulk comprises Fluorinated Ethylene Propylene (FEP) and the flexible protective covering sheets comprise Ethylene Tetrafluoroethylene (ETFE), and the sufficient heat has a temperature of at least approximately 500 degrees Fahrenheit (F.) and an upper bound of approximately 550 degrees Fahrenheit (F.).
 11. A method for sealing and smoothing a seam produced from applying flexible protective covering sheets of a fluoropolymer to a hull of a marine craft, thus forming a protective film on an exterior of the hull, said method comprising: applying sufficient heat and pressure to the seam to melt and weld the seam of fluoropolymer of adjacent flexible protective covering sheets; and smoothing the melted seam to produce a smooth seam having a smoothly sealed surface.
 12. The method according to claim 11, wherein the method comprises applying sufficient heat and pressure to an overlap seam produced from overlapping edges of adjacent flexible protective covering sheets.
 13. The method according to claim 11, wherein the method comprises applying sufficient heat and pressure to a butt-cut seam produced from butting together butt-cut edges of adjacent flexible protective covering sheets.
 14. The method according to claim 11, wherein said steps of applying sufficient heat and pressure, and smoothing the melted seam, comprise applying a soldering iron, an end of the soldering iron having a rollable wheel tip, the rollable wheel tip having a facial surface at the circumference suitably shaped for smoothing the melted fluoropolymer of the seam as the wheel tip is rolled across the seam, applying sufficient heat and pressure through the rollable wheel tip to melt and weld together the fluoropolymer of the seam.
 15. The method according to claim 11, wherein said steps of applying sufficient heat and pressure, and smoothing the melted seam, comprise applying a soldering iron, an end of the soldering iron having a chisel tip, the chisel tip suitably shaped for smoothing the melted fluoropolymer of the seam as the chisel tip is moved across the seam, applying sufficient heat and pressure through the chisel tip to melt and weld together the fluoropolymer of the seam.
 16. The method according to claim 11, wherein the flexible protective covering sheets comprise Ethylene Tetrafluoroethylene (ETFE), and the sufficient heat has a temperature of at least approximately 500 degrees Fahrenheit (F.) and an upper bound of approximately 550 degrees Fahrenheit (F.).
 17. A protected marine craft hull, comprising: a hull having an external portion covered with flexible fluoropolymer covering sheets adhered to the hull; the flexible fluoropolymer covering sheets being arranged with at least two adjacent flexible fluoropolymer covering sheets meeting and forming a seam; and the seam having a smooth and sealed surface produced through an application of sufficient heat and pressure at the seam.
 18. The protected marine craft hull of claim 17, wherein the seam comprises overlapping edges of adjacent flexible fluoropolymer covering sheets.
 19. The protected marine craft hull of claim 17, wherein the seam comprises butt-cut edges of adjacent flexible fluoropolymer covering sheets butted together.
 20. The protected marine craft hull of claim 17, wherein the flexible fluoropolymer covering sheets comprise Ethylene Tetrafluoroethylene (ETFE), and the sufficient heat has a temperature of at least approximately 500 degrees Fahrenheit (F.) and an upper bound of approximately 550 degrees Fahrenheit (F.).
 21. The protected marine craft hull of claim 17, wherein the seam has a smooth and sealed surface produced by first placing a thread of fluoropolymer caulk onto the seam and then applying sufficient heat and pressure at the seam to melt and weld the fluoropolymer caulk with the fluoropolymer of the flexible fluoropolymer covering sheets.
 22. The protected marine craft hull of claim 21, wherein the flexible fluoropolymer covering sheets comprise Ethylene Tetrafluoroethylene (ETFE), the thread of fluoropolymer caulk comprises Fluorinated Ethylene Propylene (FEP), and the sufficient heat has a temperature of at least approximately 500 degrees Fahrenheit (F.) and an upper bound of approximately 550 degrees Fahrenheit (F.).
 23. An apparatus for applying heat and pressure to a fluoropolymer seam to melt and weld the fluoropolymer of the seam into a seam having a smoothly sealed surface, comprising: a heating device having a heating surface suitable for applying the heat and pressure to the fluoropolymer seam; and a thread roll apparatus having a thread roll spool configured to have a spool of fluoropolymer caulk and a thread roll guide for guiding the fluoropolymer caulk onto the fluoropolymer seam.
 24. The apparatus of claim 23, wherein the heating device is a soldering iron, an end of the soldering iron having a rollable wheel tip for applying the heat and pressure to the fluoropolymer seam.
 25. The apparatus of claim 23, wherein the heating device is a soldering iron, an end of the soldering iron having a chisel tip for applying the heat and pressure to the fluoropolymer seam.
 26. The apparatus of claim 23 and further comprising: a thread roll apparatus having a thread roll spool configured to have a spool of fluoropolymer caulk; a thread roll guide for guiding the fluoropolymer caulk onto the fluoropolymer seam; a heating apparatus for heating at least a portion of the spool of fluoropolymer caulk; and a trowel member for spreading the fluoropolymer caulk on the seam after dispensing.
 27. An apparatus for applying heat and pressure to a fluoropolymer seam to melt and weld the fluoropolymer of the seam into a seam having a smoothly sealed surface, comprising: a heating surface for heating a portion of a flexible heat strap; and the flexible heat strap configurable to have a shape of at least one of a flat surface, a concave surface, and a convex surface for applying the heat and pressure correspondingly, to at least one of a flat fluoropolymer surface, a convex fluoropolymer surface, and a concave fluoropolymer surface.
 28. The apparatus of claim 27, wherein the flexible heat strap is coupled to a piston, the piston being movable to alter the configuration of the flexible heat strap to a flat surface, a concave surface, or a convex surface, as desired.
 29. An apparatus for sealing the seam between two abutting sheets of fluoropolymer film, said apparatus comprising: a thread roll apparatus having a thread roll spool configured to have a spool of fluoropolymer caulk; a thread roll guide for guiding the fluoropolymer caulk onto the fluoropolymer seam; a heating apparatus for heating at least a portion of the spool of fluoropolymer caulk; and a trowel member for spreading the fluoropolymer caulk on the seam after dispensing.
 30. An apparatus for applying heat and pressure to a fluoropolymer seam to melt and weld the fluoropolymer of the seam into a seam having a smoothly sealed surface, comprising: a heating device having a heating surface suitable for applying the heat and pressure to the fluoropolymer seam; and a glue gun apparatus for pre-heating a fluoropolymer caulk before application of the fluoropolymer caulk to the seam.
 31. The apparatus of claim 30, further comprising a trowel member for spreading the fluoropolymer caulk on the seam after dispensing.
 32. The apparatus of claim 30, wherein the glue gun apparatus pre-heats the fluoropolymer caulk to a temperature of at least approximately 500 degrees Fahrenheit (F.).
 33. The apparatus of claim 30, further comprising a guide adapter for use with a flexile guide rail apparatus for guiding the heating device and the glue gun apparatus along the seam.
 34. A flexible guide rail apparatus, comprising: a flexible guide rail strip adapted for guiding a heating device along a fluoropolymer seam; and at least one of a plurality of suction cups fitted to the flexible guide rail strip to allow coupling of the flexible guide rail strip to a surface.
 35. The flexible guide rail apparatus of claim 34 and further comprising a sliding carriage coupled to the flexible guide rail strip and configured to slide along the flexible guide rail strip.
 36. The flexible guide rail apparatus of claim 35, wherein the sliding carriage is configured to hold a heating device for applying heat and pressure to a fluoropolymer seam.
 37. The flexible guide rail apparatus of claim 36, wherein the heating device is a soldering iron.
 38. The flexible guide rail apparatus of claim 36, wherein the heating device is a glue gun apparatus.
 39. The flexible guide rail apparatus of claim 35, wherein the sliding carriage is configured to hold a knife an adjustable distance for cutting a fluoropolymer film.
 40. The flexible guide rail apparatus of claim 34, wherein the flexible guide rail strip may be coupled to another flexible guide rail strip to extend a length of the flexible guide rail strip.
 41. The flexible guide rail apparatus of claim 34, wherein the at least one of a plurality of suction cups is configured to be removable from the flexible guide rail strip.
 42. The flexible guide rail apparatus of claim 34, wherein the at least one of a plurality of suction cups is configured to allow diminishing of suction pressure in order to move the at least one of a plurality of suction cups to realign the flexible guide rail strip.
 43. The flexible guide rail apparatus of claim 34, wherein the flexible guide rail strip is configured with a laser to produce a visible laser beam to assist a user in guiding the heating device along a fluoropolymer seam.
 44. A glue gun apparatus for applying a pre-heated fluoropolymer caulk to a fluoropolymer seam to form a seam having a smoothly sealed surface, comprising: a glue gun having a guide adapter, the guide adapter configured to be coupled to a sliding carriage of a flexible guide rail apparatus; and the glue gun having a trowel member for spreading the pre-heated fluoropolymer caulk as the fluoropolymer caulk is dispensed from the glue gun.
 45. The glue gun apparatus of claim 44, wherein the glue gun has a laser configured to produce a laser light onto the seam to assist a user of the glue gun in guiding the glue gun along the seam.
 46. The apparatus of claim 23 and further comprising a laser configured to produce a laser light onto the seam to assist a user of the apparatus in guiding the apparatus along the seam. 